Injector for internal combustion engines



Sept. 29, 1942'. P, LORANGE 2,297,487

INJECTOR FOR INTERNAL COMBUSTION ENGINES Filed April 2'7, 1940 PatentedSept.29, 1942 INJECTOR FOR INTERNAL COMBUSTION enemas Prosper LOrange,deceased, late of Stuttgart,

Germany, Stuttgart, Property Custodian by Rudolf LOrange, executor,Germany;

vested in the Alien Application April 27, 1940, Serial No. 332,108 InGermany September 6, 1938 1 Claim.

This invention relates to injectors for internal combustion engines andis primarily, although not necessarily, concerned with injectors for usewith light fuels.

It is known to provide a nozzle witha piston valve which movesoutwardly, that is, in a divalve has the advantage that it can be ofsmaller dimensions and can be inserted from the end of the injectorremote from the nozzle. As hitherto constructed it has, however, thedisadvantage that the powerful return spring for the valve occupies arelatively'large space close to the nozzle. There is thus quite a largequantity of fuel near the nozzle which is accordingly exposed to hightemperatures, and this is particularly undesirable in the case of lightfuels having a low boiling point, since the heat of combustion tends tovaporize such fuel.-

The main object of the present invention is to provide an improvedconstruction in which the above-mentioned disadvantage is avoided.

In the improved injector according to the invention, a piston valve hasa sliding fit in a guide the, diameter of the guide bore for the guidespindle of the piston valve is smaller than that bore through whichthefuel to be injected is range the return spring, and hence the volumeof fuel surrounding it, at any desired distance from the injection endof the guide bore, which constitutes the nozzle, and to conduct the fuelto the injection end of the guide bore in such a manner as to reduce toa minimum heating of the fuel prior to injection.

The'piston valve preferably comprises a guide spindle having at leastone passage through which the fuel flows to an annular recess in theguide spindle adjacent to the control surface.

A non-return valve is preferably disposed in the path of the fuel beforeit reaches the piston valve and is subjected to the force exerted on thepiston valve by both the pressure in the combustion chamber and thepressure of the return spring for the piston valve. According to oneembodiment of the present invention the non-return valve has a conicalseat, and is separate from, but actuated by, the piston valve.

The piston valve may comprise a guide spindle portion of the guide borefor the control surface, it is diilicult to make the very small gapthrough which the fuel is uniformly injected. According to a furtherfeature of the invention, an injector is provided in which the guidebore is of uniform diameter throughout its length and both the guidespindle and the control surface of the piston valve have a sliding fittherein.

In order that the invention may be more readily understood andpractised, a preferred embodiment thereof will now be described withreference to the accompanying drawing, in which the single figureillustrates an axial sectional view of a fuel injector according to thepresent invention.

The injector illustrated comprises a housing A in which is mounted anozzle member B. The nozzle member B is retained in position in thehousing A by a member D which screws into the top of the housing A andis locked in position by a lock nut G. The construction of the member Band the housing A is such that only a small portion of the surface ofthe member B actually engages with the housing A so that the conductionof heat from the housing A to the member B is reduced to a The member Dhas a central bore through which the fuel flows, and the top end of thebore is formed as a conical seating for connection to a correspondingseating at the end of the supply pipe of the injector.

The injector is arranged to be pressed by a] ter throughout its length,and the piston valve C has a guide spindle formed on its outer surfacewith four straight grooves, between which four guideribs are left, sothat fuel supplied tothe having a control surface at one end thereof. Ifposition by a compression return spring F sura head Ci integral with theupper end of the piston valve C and a shoulder at the upper end of theguide bore in the member-B. The arrangement is such that the pistonvalve C moves downwardl'y when the pressure of the fuel delivered by thepump to the injector reaches a predetermined value, whereupon thecontrol surface J moves beyond the injection end of the bore in themember B to permit the injection of the fuel.

In the embodiment illustrated, a non-return valve H having a conicalseating is employed, and in this case, in order to avoid the possibilityof jamming of the piston valve in its bore, the conical non-return valveH is made separate from the piston valve C. The valve H is arranged tobe pressed against its seating by the head C1 of the piston valve C, theupper surface of the head C1 advantageously being formed as a part of asphere. The non-return valve H is subjected to the force exerted on thepiston valve by both the pressure in the combustion chamber and thepressure of the return spring F.

Any suitable arrangement of grooves may be employed on the outer surfaceof the guide spindle, provided that the guide spindle of the pistonvalve C guides the control surface J so that said control surface movescoaxially with the guide bore and, in its closed position, forms afluid-tight fit therein.

Prior. to the commencement of injection, the non-return valve, that isthe conical valve H in the arrangement illustrated is loaded on one sidewith' the full pump pressure, while the pressure in the combustionchamber and the return spring F act on the other side thereof. As soonas the non-return valve opens, however, only the differential pressuredue to the velocity of the flow of the fuel acts on the non-return valveto press it against the return spring F, the pressure being exertedindirectly through the intermediary of the head C1 in the constructionillustrated.

Since the piston valve C remains closed slightly longer than thenon-return valve owing to the relative arrangement of the controlsurface J and the co-operating portion of the injection end of the guidebore, the piston valveC is loaded on one side upon the opening of thenon-return valve by the pump pressure reduced by the pressure 'dropacross the non-return valve, and on the other side by the pressure inthe combustion chamber and the return spring F.

Immediately the piston valve C opens, that is when the control surface Jmoves beyond the injection end of the guide bore, the area of the2,297,487 rounding the valve spindle and disposed between annularpassage through which the fuel is injected determines the pressureopposing that of the return spring F. The piston valve-C will alwaysopen to such an extent that the area of the passage for the injection offuel is such that the velocity of flow produces a hydraulic pressure onthe valve equal and opposite to the returning force exerted by thespring F. It is thus possible by suitable selection of the strength ofthe return spring F to produce a predetermined relationship between theinjection velocity of the fuel with a small opening of the piston valveC and the injection velocity with a larger opening of the piston valveC. In any case, the highest velocity of the fuel produced by thepressure is utilised for atomisation of the fuel, and only thesubstantially smaller fraction of flow energy which is produced at theopening through which the fuel is injected is lost.

What is claimed as the invention and desired secured by Letters Patentof the United States is:

An injector for light fuels comprising a nozzle having an axial borethrough which fuel to be injected is delivered under pressure, said boreincluding an upper portion, an intermediate portion of enlarged diametercommunicating with said upper portion, and a lower guide portioncommunicating with said intermediate portion; a valve seat adjacent thejuncture between said upper and intermediate portions; a non-returnvalve cooperating with said valve seat to control the flow of fuel fromthe. upper portion to the intermediate portion of the bore; a pistonvalve slidably mounted within said guide and intermediate portions andincluding a passage through which fuel may flow from said intermediateportion to the lowermost end of said guide portion, said piston valvehaving a head at its upper end disposed within the intermediate portionof the bore and beneath the non-return valve positioned within saidportion, and said piston valve having a valve surface at its lower endfor controlling the flow of fuel from the lowermost end of the bore; anda compression return spring within Executor of the Estate of ProsperLOrange,

Deceased.

